Add Java code template programmatically

Question

I like when Eclipse lets me jump between parameters in a method call using a Tab key. I would like my plugin to provide a similar functionality. To be precise, I am injecting some piece of text into the editor and I would like to highlight specific syntax and let the programmer jump to the next match using the Tab key.

Here is an example. Lets suppose I dynamically created the following snippet:

String a = "bogus string";
int i = a.[?]

I will inject that into the editor and I would like that [?] is highlighted and ready for modification (user might type length()). Moreover, if there is more [?] fragments, I would like user to use Tab to move to the next one.

After researching a bit, I found that it might be done using templates. However, I can't find any relevant examples on the Web. Does anybody have experience with this?

UPDATE:

I found two links that might be useful, although I am still not able to come up with a solution.

link one

link two

jeeeyul · Accepted Answer · 2012-11-02 04:12:36Z

8

+50

Sample Handler Codes:

AbstractTextEditor activeEditor = 
        (AbstractTextEditor) HandlerUtil.getActiveEditor(event);

ISourceViewer sourceViewer = 
        (ISourceViewer) activeEditor.getAdapter(ITextOperationTarget.class);

Point range = sourceViewer.getSelectedRange();

// You can generate template dynamically here!
Template template = new Template("sample", 
        "sample description", 
        "no-context", 
        "private void ${name}(){\r\n" + 
        "\tSystem.out.println(\"${name}\")\r\n"
        + "}\r\n", true);

IRegion region = new Region(range.x, range.y);
TemplateContextType contextType = new TemplateContextType("test");
TemplateContext ctx =
    new DocumentTemplateContext(contextType, 
        sourceViewer.getDocument(), 
        range.x, 
        range.y);

TemplateProposal proposal 
    = new TemplateProposal(template, ctx, region, null);

proposal.apply(sourceViewer, (char) 0, 0, 0);

Result:

enter image description here

I suggest you use org.eclipse.jdt.ui.javaCompletionProposalComputer extension. It allows you can contribute Template more legal way.

In my codes, there are hacks since there is no way to get ISourceViewer legally. I know ISourceViewer is ITextTargetOperation itself, but it is not API(Illegal Casting). And Template is intended to designed to be used by TemplateCompletionProcessor or TemplateCompletionProposalComputer.

answered Nov 2, 2012 at 4:12

jeeeyul

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1 Comment

Jeyakumar Kasi Over a year ago

@jeeyul When creating the sourceViewer using ITextOperationTarget.class, the caret offset value is not accurate and it ignores the folded lines (e.g. import statement). Any suggestions to get the current offset with folded lines as well?

sbridges · Accepted Answer · 2012-10-27 02:55:48Z

1

I'm not entirely sure what you want, but you may be able to do what you want with templates.

For example, open a java editor, place the cursor inside a method, type arraya then ctlr-space, and select arrayadd from the pop up menu. You will get a template with String highlighted, pressing tab jumps to the next variable. The template source can be seen in,

Preferences -> java -> editor ->templates

${array_type}[] ${result:newName(array)} = new ${array_type}[${array}.length + 1];
System.arraycopy(${array}, 0, ${result}, 0, ${array}.length);
${result}[${array}.length]= ${var};

Everything starting the a $ is a variable that you can fill in, and you can tab between variables while filling in the template.

answered Oct 27, 2012 at 2:55

sbridges

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4 Comments

zpavlinovic Over a year ago

Yes, this is how templates work. However, I am developing a plugin that will create code snippets on runtime. I am trying to find out how to, if possible, utilize templates API so user can modify and navigate between placeholders. Is there some more information you would like me to give?

sbridges Over a year ago

The best bet is to track down the source of the template plugin, and see how it works then.

jeeeyul Over a year ago

Did you check org.eclipse.jface.text.templates.TemplateProposal? What if you want to insert snippet not using content assist, You can inspect TemplateProposal#apply() method also.

zpavlinovic Over a year ago

I am injecting my snippet directly into the editor on a specific location without using content assist, so this looks really promising. If you could give some code example in an answer, I will accept it.

32kda · Accepted Answer · 2018-03-09 11:31:59Z

My answer is based on jeeeyul's answer. The difference is that I wanted not only template itself, but also imports for it to be resolved and added automatically. This can be done in following way, using JDT stuff:

AbstractTextEditor activeEditor = 
            (AbstractTextEditor) HandlerUtil.getActiveEditor(event);
    if (activeEditor == null) {
        return null;
    }
    ITypeRoot element = EditorUtility.getEditorInputJavaElement(activeEditor, true);
    if (element == null) {
        return null;
    }
    ICompilationUnit unit = element.getAdapter(ICompilationUnit.class);
    if (unit == null) {
        return null;
    }
    ISourceViewer sourceViewer = (ISourceViewer) activeEditor.getAdapter(ITextOperationTarget.class);
    Point range = sourceViewer.getSelectedRange();
    // You can generate template dynamically here!
    Template template = new Template("new List", "Add new list creation", JavaContextType.ID_STATEMENTS,
            "List<${type}> ${name:newName(java.util.List)} = new ArrayList<${type}>();${:import(java.util.List, java.util.ArrayList)}",
            true);
    IRegion region = new Region(range.x, range.y);
    JavaContextType contextType = new JavaContextType();
    contextType.setId(JavaContextType.ID_STATEMENTS); //Set context type, for which we apply this template
    contextType.addResolver(new ImportsResolver("import","import")); //Add imports resolver if we want imports to be added automatically for some template
    CompilationUnitContext ctx = new JavaContext(contextType, sourceViewer.getDocument(), range.x,
            range.y, unit);
    TemplateProposal proposal = new TemplateProposal(template, ctx, region, null);
    proposal.apply(sourceViewer, (char) 0, 0, 0);

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